1. Field of the Invention
The present invention generally relates to medical patches, and more specifically relates to medical patch systems and methods that enable patients to self-locate and apply a series of replacement medical patches.
2. Description of the Related Art
Medical delivery patches are generally used for nerve stimulation, and delivering pharmacological agents such as pain medication, drugs, and hormones. Medical patches are often adhered to a patient's skin surface with an operating portion of the patch directed toward a target location on the patient. Over a period of time, the medical patches deliver the nerve stimulation or the pharmacological agents to the patient for achieving a therapeutic benefit. In some instances, a series of medical patches are applied to the patient, whereby a first medical patch applied by a medical professional is removed from a patient's skin and replaced with a second medical patch. Eventually, the second medical patch may be removed and replaced by a third medical patch and so on. The application of the second medical patch is often done by the patient at home. Due to inexperience in properly placing replacement medical patches, the replacement medical patch may be improperly aligned over the target location on the patient, e.g. a particular nerve that is the target for nerve stimulation. In addition, medical patches are often adhered using adhesive layers. Skin irritation may occur if the adhesive layer on a second or subsequent patch contacts the same area of skin that was contacted by the adhesive layer from an earlier applied patch.
FIG. 1 shows a conventional medical patch 20, such as a medical patch used for neurostimulation, having a centrally located cathode 22 and a ring-shaped anode 24 that surrounds the cathode 22. The cathode 22 and the anode 24 are mounted on a support structure 26, such as a polyimide circuit, to form the concentric skin electrode patch 20. The medical patch 20 may be constructed from well-known electrode materials such as silver, silver/silver chloride, gold, titanium, or other conductive materials. The medical patch may also be made of conductive polymers, fibers and the like. The medical patch 20 may be a stand-alone component that is attached to a stimulation generator via a cable, as described in commonly owned U.S. patent application Ser. No. 11/146,522, the disclosure of which is hereby incorporated by reference herein. In instances where the medical patch 20 is incorporated into a flexible circuit, the flexible circuit may contain all of the required electronics required for generating stimulation signals. The flexible circuit may include mounting regions for receiving battery cells.
As shown in FIG. 1, the medical patch has an outer perimeter 30 and an adhesive layer 32 that extends around the outer perimeter 30. The adhesive layer 32 is used to attach the medical patch to a patient. In most instances, the adhesive layer 32 is placed in contact with the patient's skin for attaching the medical patch 20 to the patient. In many instances, after a period of time, it is necessary to remove the medical patch 20 and replace it with a second medical patch. If the replacement procedure is completed by the patient, and not medical personnel, the patient may not properly align the cathode 22 and the anode 24 over the target location on the patient's body. Even if the patient does properly position the medical patch on the skin, the adhesive layer 32 on the replacement patch is placed over the same location on the skin as the prior patch, which may cause skin irritation.
As is known to those skilled in the art, conventional medical patches such as those shown in FIG. 1 have one or more limitations. First, because the medical patches are affixed to the skin by means of adhesives, prolonged ambulatory use of these patches causes skin irritation due to the adhesives being affixed to the same location on the skin. Moreover, because the specific nerves to be stimulated can only be stimulated over a very small area, precise placement of the delivery patch is essential in order for the electrode to be therapeutic. Unfortunately, it is difficult for patients to perform precise placement of the replacement patches at home. Thus, better therapeutic results are obtained when using earlier placed medical patches than when using replacement medical patches.
In view of the foregoing, there is a need for a medical patch system and methods that provide for precise and repeatable placement of medical patches, whereby replacement medical patches are efficiently placed and aligned over a target location on a patient's body. Moreover, there is a need for medical patch systems and methods that cause minimal or no skin irritation during prolonged used. In addition, there is a need for medical patch systems and methods that enable patients to use tactile senses to identify the various parts of the patch, especially in instances where the patches are not visible to the user.